This patch adds the missing code comment for memory barrier WARNING: memory barrier without comment + mb();
WARNING: memory barrier without comment + mb(); Cc: Guchun Chen <guchun.c...@amd.com> Cc: Christian König <christian.koe...@amd.com> Cc: Alex Deucher <alexander.deuc...@amd.com> Cc: "Pan, Xinhui" <xinhui....@amd.com> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmu...@amd.com> --- v3: Corrected title message drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 4f818f13dc9d..bb65e12ed027 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -305,10 +305,17 @@ size_t amdgpu_device_aper_access(struct amdgpu_device *adev, loff_t pos, if (write) { memcpy_toio(addr, buf, count); + /* Make sure contents of system memory are copied/flushed + * without messing up order of writes to PCI device I/O memory + */ mb(); amdgpu_device_flush_hdp(adev, NULL); } else { amdgpu_device_invalidate_hdp(adev, NULL); + /* Make sure contents of system memory drained/invalidated + * before copying contents from PCI device I/O memory + * to system memory + */ mb(); memcpy_fromio(buf, addr, count); } -- 2.25.1